Characteristics of Flowfield and Output Power of a Supersonic Flow Chemical Oxygen-Iodine Laser

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Possibility of mixing enhancement of iodine with singlet oxygen by means of acoustic excitationwas examined using a jet-diffusion flame of methane. The jet-diffusion flame was acoustically excited by monotone sound wave generated by a loud speaker. Applying the acoustic excitation using a specific range of frequency that corresponds to the Strouhal number St=0.15 to 0.6, the jet diffusion flame has peculiar features. In the mode of increasing the jet velocity, the flame shortens its original length and widened in the incident direction of sound wave. Decreasing the jet velocity, the jet velocity at which the reattachment of lifted flame occurs is lowered significantly owing to the acoustic excitation, and the lifted flames with elliptical cross sections or branched tips are discovered in the specific region of the velocity and sound frequency.A Q-switched supersonic flow chemical oxygen-iodine laser is also simulated by solving the gas flow model coupled with the precis e chemical kinetic model and the optical model. The model includes the effects of hyperfine relaxation and velocity cross relaxation for iodine atoms. The effects of such relaxations and nonuniformity of the three-dimensional flow field on the power extraction were discussed. The results show that the peak power under the influence of hyperfine relaxation and velocity cross relaxation, which is normalized to the corresponding continuous wave value, is 15. It agrees fairly well with common experimental results of Q-switched chemical oxygen-iodine laser operation. The peak power of the pulse in the three-dimensional flow field is considerably small compared to that in the equivalent one-dimensional flow field and the pulse is widened roughly twice due to insufficient mixing, shock waves, expansion waves and wakes.